1. Field of the Invention
This invention relates to electric motors and to methods and apparatus for the cooling thereof, particularly of totally enclosed motors and finds particular utility applied to motors having a single airgap.
2. Description of the Prior Art
In our Herr and Jaffe U.S. Pat. No. 3,891,876 issued June 24, 1975 and assigned to the assignee of the present application, there is described and disclosed permanent magnet DC motors characterized by small size, light weight, high torque-to-inertia ratio, long brush life and freedom from inherent electromagnetic interference utilizing opposing rare-earth-alloy magnets to define therebetween a single airgap having rotationally supported therein a non-ferromagnetic, low inertia armature. An improved armature structure for such motor is described and disclosed in our Herr and Jaffe U.S. Pat. No. 4,063,123 dated Dec. 13, 1977 and assigned to the assignee of the present invention.
Totally enclosed motors have long been known in the prior art and it has long been recognized to be desirable to provide special construction thereto for enhanced heat transfer to thereby restrict the temperature rise of the motor and of the various parts thereof during operation. Each of the prior art arrangements, however, have been limited by the basic requirements of essentially circular symmetry of the iron housing surrounding the armature of conventional iron core motor designs, the essentially poor heat transfer characteristics of iron, and the high hysteresis losses and the resultant high heat generation within conventional iron core armature structures.